Method of producing polychromatic screens and the like



Patented Oct. 27, 1931 PATENT OFFICE. v

ALLEN A. CANTON, orimw YORK, N. Y.

jmnrnonflor rnonucme roLYcHRoMArIc sonnnns ANID'THE L nn screen or filter by means of which colored pictures are obtainable directly and without the use or intervention of special prisms, lenses or mirrors. 3 7 A further object of the invention is to pro- 16 duce' a polychromatic screen by a process whichis not only inexpensive and simple to carry out but which also results in the production-of color filters wherein all of the IC-Iprimary colors may be effectively utilizedi 20 to produce colored picturesmuchmore perfectly and with greater efliciency than has been possibleheretofore. i I

I A still further object of'the invention is :"nIthe provision of an improved and simplifiedmethod of applying minute dots of vari ous colors upon the surface of a photographic film orlight filter, the colordots being so appliedand of such character that they do. not cause distortion of the light rays proiii jected therethrough norappear as distinct spots of color when the icture is projected inmagnified form upon t e regular screen.

Otherobj ects and advantages of the present T-Ilinvention will appear more fully hereinafter. It will,of course, be-understood'that the present invention-relates to the treatment of color filters or light screens, the base or body of WhlChumtly be ofglass, celluloid or other qgappropriate material suitable for color 40 photography andthe projection of colored pictures upon a'xsuitable screen. In ordinarypractice the color filmor light screen with which the present invention is coni cerned consists ofa film of gelatin, collodion or thelike which is superposed upon a suitable light-transparent support therefor.

Heretofore and [prior to this invention polychromatic filters have been produced by agapplying variously colored starch or similar particles to the surface thereof. These starch 1929. Serial No. 365,578.

particles are of such size, however, that they interfered with the rapid transmission of light through the filter so treated and at the same time caused distortion of the light rays projected therethrough. In order to obviate these and other objections and to attain the aforestated objects in the most effective manner, the present invention provides a method by which the surface of the color screen or filter is covered or stained with variously colored'microscopic dots or spots, the latter being so thin and of suchuniform character as not to absorb too much of or distort the a light rays projected therethrough.-

The practical manufacture of color filters produced in accordance with the present in-,

'vention is carriedout as follows: minute particles of ironiorothersuch magnetic material are passed rapidly through a suitable oxidizing agent with the result that the surfaces of these particlesv are oxidized." The particles of magnetic material so oxidized are. then stained with variously colored dyes, the dyes employed for this purpose being preferably soluble in ether and of the primary colors There are thus obtained severalgroups of differently colored particles. Approximate ly equal quantities of these variously colored particles (such as red, yellow and blue,'or orange, green and violet or other combinations of the primary colorsof the spectrum) are then thoroughly mixedtogether. This mixture of the colored particles of iron is then. applied directly to the surface of the color filter or screen, the application of said particles to the surface of the filter being by spraying, brushing, or the equivalent thereof. Preliminarily to applying these colored particles to the filter'surface, the latter is preferably slightly -moistened with ether which assists inremoving the dye from the;

iron particles, thereby producing colored stains or spots of microscopic size upon the surface'upon which the particles have Men applied. A magnet, which is brought into close proximity with the surface of the, color filter or screen, is employed for removing surface being freed of all particles or elementswhicho of themselves might cause disall of the iron particlesfrom the filter, the i subjected said particles to the influence of an oxidizing agent. Itis preferable, however, to partially oxidize the magnetic particles for the reason that the dyes are the more easily retained thereby. I have also mentioned that it is preferable to employ dyes which are soluble in ether and that the dyed magnetic particles are applied to a color filter, the surface of which has been slightly moistened with ether.. It will, of course, be understood that dyes may be employed which are soluble in a medium other than ether and that the surface of the filter is treated with the solvent for these dyes preliminarily to applying the dyed particles thereto. The important point to be observed is that the dyestuffs with which the magnetic particles are stained have a less powerful ailinity for said particles than for the medium with which the filter surface has been treated prior to the step of applying the stained particles thereto. the function of the magnetic particles being merely to serve as vehlcles for transmitting the various'dyes to the surface of the filter.

Inasmuch as the conveying medium for the dye to the filter is of magnetic material it becomes a simple expedient to remove these dye conveying vehicles through the employment of a sufficiently powerful magnet. The

surface of the filter is thus left with only microscopic dots of various colors none ofwhich overlap each other and all'of which cooperate to produce a polychromatic film of uniform character and infinitesimal depth. These microscopic dots of color do not show as color blotches when magnified for moving picture screen work, nor do they absorb so much light as to increase the time of exposure to such eX- tent that the film cannot be employed in the taking of motion pictures.

It will be understood, of course, that the invention is susceptible of various changes and modifications without departing from the real spirit or principles thereof,and it is accordingly intended to claim the invention broadly aswell as specifically as indicated by the appended claims. 7

lVhatis claimed as'new and useful is 1. The process of manufacturing polychro-v matic films forcolor photography which consists in applying vari colored magnetic par-. ticles to the surface of the film whereby to transfer the colorfrom said particles to said film and then removing said particles by means of a magnet, said particles being initially prepared by dividing the same into several groups respectively stained with differently colored dye-stuffs.

2. The process of manufacturing polychromatic films for color photography which consists in transmitting spots of various colors to the surface of the film by means of varicolored particles of magnetic material, ap

plied directly to said surface and adapted to e removed by magnetic attraction, said particles being initially prepared by respectively staining batches of the same with differently colored dye-stuffs.

3. The process of manufacturing polychromatic films for color photography which consists in staining miscroscopic particles of magnetic material with various colors, applying said particles to the surface to be treated, whereby to effect a transference of said colors to said surface and then removing said particles by magnetic attraction, said particles being initially prepared by separating the same into several batches, staining each batch with a diiferent color, and mixing the different-1y colored batches together.

4. The process of manufacturing polychromatic films for color photography which consists in respectively staining batches of magnetic particles with differently colored dyestuffs, applying said differently colored particles indiscriminately to a surface to be treated having a greater afiinity for said dyestuffs than have said particles, and removing said particles by magnetic attraction.

5. The process of producing color films which consists in subjecting particles of magnetic material to the influence of an oxidizing agent whereby to oxidize the same, respec tively staining the oxidized surfaces of several batchs of said particles with variously colored dyestuffs, then indiscriminately applying said variously stained particles to a surface having a greater aflinity for said dyestufl's than have said particles, then magnetically removing said particles after said dyestuffs have been absorbed by said surface.

6. The process of producing filters which consists in staining particles of magnetic material divided into several groups with soluble dyestuffs of various colors, each group being diflerently colored, moistening the surface to be treated with a solvent for said dyestuffs. indiscriminately applyingsaid variously stained particles to said moistened sursaid particles to said surface, and finally removing said particles by magnetic attraction.

7. The process of producing color filters which consists in staining minutev particles of iron divided into groups with variously colored ether soluble dyestufls, each group being differently colored, moistening the surface to be colored with ether, indiscriminategaseous 1y applyingsaid variously stained articles of iron to said moistened surface, an removing said iron particles by magnetic attraction after said dyestuffs have been absorbed by said surface. I

In testimony whereof, I have hereunto affixed my signature.

ALLEN A. CANTON. 

